318 lines
20 KiB
C++
318 lines
20 KiB
C++
//
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// Copyright 2020 Electronic Arts Inc.
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//
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is free
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// software: you can redistribute it and/or modify it under the terms of
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// the GNU General Public License as published by the Free Software Foundation,
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// either version 3 of the License, or (at your option) any later version.
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
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// in the hope that it will be useful, but with permitted additional restrictions
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// under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
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// distributed with this program. You should have received a copy of the
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// GNU General Public License along with permitted additional restrictions
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// with this program. If not, see https://github.com/electronicarts/CnC_Remastered_Collection
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/* $Header: /CounterStrike/RNDSTRAW.CPP 1 3/03/97 10:25a Joe_bostic $ */
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/***********************************************************************************************
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*** C O N F I D E N T I A L --- W E S T W O O D S T U D I O S ***
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***********************************************************************************************
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* *
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* Project Name : Command & Conquer *
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* *
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* File Name : RNDSTRAW.CPP *
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* *
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* Programmer : Joe L. Bostic *
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* *
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* Start Date : 07/04/96 *
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* *
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* Last Update : July 10, 1996 [JLB] *
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* *
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*---------------------------------------------------------------------------------------------*
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* Functions: *
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* RandomStraw::Get -- Fetch random data. *
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* RandomStraw::RandomStraw -- Constructor for the random straw class. *
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* RandomStraw::Reset -- Reset the data to known initial state. *
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* RandomStraw::Scramble_Seed -- Masks any coorelation between the seed bits. *
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* RandomStraw::Seed_Bit -- Add a random bit to the accumulated seed value. *
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* RandomStraw::Seed_Bits_Needed -- Fetches the number of seed bits needed. *
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* RandomStraw::Seed_Byte -- Submit 8 bits to the random number seed. *
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* RandomStraw::Seed_Long -- Submit 32 bits to the random number seed. *
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* RandomStraw::Seed_Short -- Submit 16 bits to the random number seed. *
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* RandomStraw::~RandomStraw -- Destructor for random straw class. *
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* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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#include <limits.h>
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#include <string.h>
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#include "rndstraw.h"
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#include "sha.h"
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/***********************************************************************************************
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* RandomStraw::RandomStraw -- Constructor for the random straw class. *
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* *
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* This will initialize the random straw into a known state. The initial state is useless *
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* for cryptographic purposes. It must be seeded before it should be used. *
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* *
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* INPUT: none *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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RandomStraw::RandomStraw(void) :
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SeedBits(0),
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Current(0)
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{
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Reset();
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}
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/***********************************************************************************************
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* RandomStraw::~RandomStraw -- Destructor for random straw class. *
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* *
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* This destructor will clear out the seed data so that there won't be any sensitive *
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* information left over in the memory this object occupied. *
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* *
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* INPUT: none *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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RandomStraw::~RandomStraw(void)
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{
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Reset();
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}
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/***********************************************************************************************
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* RandomStraw::Reset -- Reset the data to known initial state. *
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* *
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* This routine is functionally equivalent to performing an placement new on the object. It *
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* clears out all the seed data. *
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* *
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* INPUT: none *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: You must reseed it before fetching random numbers. *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Reset(void)
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{
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SeedBits = 0;
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Current = 0;
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memset(Random, '\0', sizeof(Random));
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}
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/***********************************************************************************************
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* RandomStraw::Seed_Bits_Needed -- Fetches the number of seed bits needed. *
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* *
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* This routine is used when seeding the random straw. Keep feeding random bits to this *
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* class until the Seed_Bits_Needed value returns zero. Random bits should be gathered from *
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* sources external to the immediate program. Examples would be the system clock (good for *
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* a few bits), the delay between player keystrokes (good for a few bits per keystroke), *
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* etc. When gathering random bits from integers, use the low order bits (since they *
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* characteristically are less predictable and more 'random' than the others). *
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* *
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* INPUT: none *
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* *
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* OUTPUT: Returns with the number of bits required in order to fully seed this random *
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* number generator. *
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* *
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* WARNINGS: Even if this routine returns zero, you are still allowed and encouraged to feed *
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* more random bits when the opportunity arrises. *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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int RandomStraw::Seed_Bits_Needed(void) const
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{
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const int total = sizeof(Random) * CHAR_BIT;
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if (SeedBits < total) {
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return(total - SeedBits);
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}
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return(0);
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}
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/***********************************************************************************************
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* RandomStraw::Seed_Bit -- Add a random bit to the accumulated seed value. *
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* *
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* This routine should be called to feed a single random bit to the random straw object. *
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* You must feed as many bits as requested by the Seed_Bits_Needed() function. Submitting *
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* additional bits is not only allowed, but encouraged. *
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* *
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* INPUT: seed -- The bit (lowest order bit) to feed to the random number seed. *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Seed_Bit(int seed)
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{
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char * ptr = ((char *)&Random[0]) + ((SeedBits / CHAR_BIT) % sizeof(Random));
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char frac = (char)(1 << (SeedBits & (CHAR_BIT-1)));
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if (seed & 0x01) {
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*ptr ^= frac;
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}
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SeedBits++;
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if (SeedBits == (sizeof(Random) * CHAR_BIT)) {
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Scramble_Seed();
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}
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}
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/***********************************************************************************************
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* RandomStraw::Seed_Byte -- Submit 8 bits to the random number seed. *
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* *
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* This will submit 8 bits (as specified) to the random number seed. *
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* *
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* INPUT: seed -- The seed bits to submit. *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Seed_Byte(char seed)
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{
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for (int index = 0; index < CHAR_BIT; index++) {
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Seed_Bit(seed);
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seed >>= 1;
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}
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}
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/***********************************************************************************************
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* RandomStraw::Seed_Short -- Submit 16 bits to the random number seed. *
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* *
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* This will submit 16 bits to the accumulated seed. *
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* *
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* INPUT: seed -- The 16 bits to submit to the seed. *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Seed_Short(short seed)
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{
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for (int index = 0; index < (sizeof(seed)*CHAR_BIT); index++) {
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Seed_Bit(seed);
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seed >>= 1;
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}
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}
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/***********************************************************************************************
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* RandomStraw::Seed_Long -- Submit 32 bits to the random number seed. *
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* *
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* This will submit a full 32 bits to the accumulated seed value. *
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* *
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* INPUT: seed -- The 32 bits to submit. *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Seed_Long(long seed)
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{
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for (int index = 0; index < (sizeof(seed)*CHAR_BIT); index++) {
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Seed_Bit(seed);
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seed >>= 1;
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}
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}
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/***********************************************************************************************
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* RandomStraw::Scramble_Seed -- Masks any coorelation between the seed bits. *
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* *
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* This routine is called when a full set of seed bits has been accumulated. It will take *
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* the existing seed and scramble the bits. An effective way of doing this is to use the *
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* Secure Hash Algorithm. It is necessary to have this routine because there might be *
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* some coorelation in the seed bits. Even more important is that this routine will result *
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* in every bit of the seed having a scrambling effect on every other bit. *
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* *
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* INPUT: none *
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* *
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* OUTPUT: none *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/10/1996 JLB : Created. *
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*=============================================================================================*/
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void RandomStraw::Scramble_Seed(void)
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{
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SHAEngine sha;
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for (int index = 0; index < sizeof(Random); index++) {
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char digest[20];
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sha.Hash(&Random[0], sizeof(Random));
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sha.Result(digest);
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int tocopy = sizeof(digest) < (sizeof(Random)-index) ? sizeof(digest) : (sizeof(Random)-index);
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memmove(((char *)&Random[0]) + index, digest, tocopy);
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}
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}
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/***********************************************************************************************
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* RandomStraw::Get -- Fetch random data. *
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* *
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* This routine will fetch random data and store it into the buffer specified. *
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* *
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* INPUT: source -- Pointer to the buffer to fill with random data. *
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* *
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* length -- The number of bytes to store into the buffer. *
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* *
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* OUTPUT: Returns with the actual number of bytes stored into the buffer. This will always *
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* be the number of bytes requested since random numbers are unexhaustible. *
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* *
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* WARNINGS: none *
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* *
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* HISTORY: *
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* 07/04/1996 JLB : Created. *
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* 07/10/1996 JLB : Revamped to make cryptographically secure. *
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*=============================================================================================*/
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int RandomStraw::Get(void * source, int slen)
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{
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if (source == NULL || slen < 1) {
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return(Straw::Get(source, slen));
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}
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int total = 0;
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while (slen > 0) {
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*(char *)source = (char)Random[Current++];
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Current = Current % (sizeof(Random) / sizeof(Random[0]));
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source = (char*)source + sizeof(char);
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slen--;
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total++;
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}
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return(total);
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}
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